<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #d1{
            width: 200px;
            height: 200px;
            border: 1px solid red;
            border-radius:200px;

        }
        #d2{
            width: 50px;
            height: 50px;
            border: 1px solid red;
            padding-left: 50px;
            padding-top:50px;
        }
    </style>
</head>
<body>
<ul>
    <li>aaa</li>
    <li>bbb</li>
    <li>ccc</li>
</ul>
<!--div#d1 div.c1-->
<div id="d2">内边距</div>
<div id="d1">边框测试</div>

</body>
</html>